The present invention relates to electric motors; and more particularly, to the brush assembly of electric motors.
Electric motors are used in a variety of applications, including power tools. Such electric motors typically include a motor shaft, a motor armature, magnets, a fan baffle, a commutator assembly, brushes and electrical leads. The electrical leads selectively link brushes to a power source. The motor armature is fixed for rotation with the motor shaft and a series of copper conducting wires are wound in various patterns about peripheral slots. Ends of the wires are fused to the commutator. The commutator is fixed for rotation with the motor shaft and provides an electrical connection between the rotating armature and the stationary brushes.
The brush is often held in place by an electrically conductive brush box. The electrical current powering the motor flows through this electrically conductive brush box through the brushes and into the commutator. As a result, the temperature of the brush box (which is typically made of brass) can be raised to fairly high levels; particularly when high amperage applications are concerned like battery operated power tools. As such, the temperature of the brush box can be sufficient to potentially damage the field case housing. Thus, it is desirable to minimize any such risk of damage.
In accordance with one aspect of the present invention, an electric motor brush assembly is provided. The assembly includes an electrically conductive brush box and at least one crimping tab. A base member has an upper surface and an oppositely disposed crimping surface. The electrically conductive brush box is located against the upper surface and has a portion of the crimping tab located against the oppositely disposed crimping surface. A field case housing has a seat with a retention member adapted to retain the base against the seat. A spacer member is adapted to space the portion of the crimping tab against the crimping surface away from the field case housing.
In accordance with another aspect of the present invention, an electric motor brush assembly with an electrically conductive brush box, a biasing member holder, and at least one crimping tab adjacent the biasing member holder is provided. A base member has an upper surface and an oppositely disposed crimping surface. The electrically conductive brush box is located against the upper surface and has a portion of the crimping tab located against the oppositely disposed crimping surface. A field case housing is adapted to retain the base member.
In accordance with one aspect of the present invention, an electric motor brush assembly with an electrically conductive brush box adapted to hold a brush and having at least one crimping tab is provided. A base member is formed of high temperature resistant plastic and is adapted to cooperate with the crimping tab to retain the brush box against a surface of the base member. A field case housing has a seat and the base member is located against the seat. A screw member has a head and is threaded into the field case housing such that the head presses against a surface of the base member to retain the base member in the seat. The screw member is located in non-contacting relationship with the electrically conductive brush box.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.